• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.2
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• pp.33-43
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• 2002

현대의 레이다나 통신 시스템에 있어 위상 배열안테나는 필수 구성요소이고 이러한 위상 배열 안테나에는 수 천개의 독립적인 위상제어기가 사용되어지고 있다. 따라서 대량생산이 가능하면서도 성능이 우수한 저손실, 저가격의 True-Time Delay (TTD)를 지원하는 위상천이기가 크게 요구되고 있는 실정이다. 최근 몇 년 동안 MEMS 공정을 이용한 저손실 RF 스위칭 소자와 가변 캐패시터가 성공적으로 개발되었으며 이러한 저손실의 MEMS 스위칭 소자를 이용한 위상천이기 구현이 가능하게 되었다. 본 논문에서는 크기나 전력소모, 삽입손실 등에서 우수한 고주파 특성을 갖는 RF MEMS (Micro-Electro Mechanical System) 스위치에 대해서 간략히 언급하고 이를 이용한 위상천이기와 기존의 위상천이기를 비교 분석하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.91-94
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• 2005

디지털 기술의 발전에 따라 방송 통신 융합이 가속화되고 있다. 우리나라는 방송 통신의 융합을 위해 쌍방향성을 제공하는 IP-TV와 같은 서비스가 유선 인터넷망을 사용한 홈오토메이션의 고정 환경 서비스를 중심으로 이루어지고 있다. 그러나 자동차 또는 휴대폰 등의 이동형 디지털 TV에서의 양방향 데이터 서비스 같은 방송통신 융합 서비스를 제공하기 위해서는 유선인터넷과 비슷한 전송속도와 비용을 갖는 무선 인터넷 서비스가 필요하다. 우리나라는 2006년 상반기에 유선인터넷과 비슷한 전송속도와 비용을 갖는 무선인터넷 서비스인 휴대인터넷을 상용화할 예정이다. 휴대인터넷은 동일한 주파수 대역을 이용하여 송수신을 하는 TDD방식을 사용한다. 우리나라는 셀룰러 시스템의 발달로 FDD를 중심으로 부품의 개발과 연구가 진행되어 왔기 때문에 TDD용 부품의 개발과 연구가 필요하다. 본 논문에서는 TDD 기반의 휴대인터넷용 고출력 RF 스위치의 개발에 대하여 기술한다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.282-283
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• 2007

본 논문에서는 저전압에서 구동 할 수 있는 압전구동 방식의 RF MEMS 스위치를 설계하였다. 설계는 유한요소기법(FEM)을 지원하는 시뮬레이터 (ConventorWare)를 사용하여 수행하였고, 이를 바탕으로 deflection, contact force, stress 등 기계적인 해석을 함으로써 최적화된 설계를 할 수 있었다. 이번 설계에서는 적절한 contact force를 유지하면서 hinge에서 받는 stress를 최소화하기 위하여 구동기를 2개 사용한 듀얼형식의 모델을 제안하였고, hinge의 모양은 'ㄷ'로 하여 deflection을 향상시켰다. 이 듀얼형식의 최적화된 모델은 signal line과 contact pad 간의 gap이 3.4${\mu}m$일 때, 최초 2.8V에서 contact이 이루어졌으며, 5V에서 12.4${\mu}N$의 contact force와 116MPa의 stress를 얻었고, 차후, SP4T나 SP6T 등의 설계시 공간 효율이 높은 다양한 형태의 구조를 설계할 수 있다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.223-228
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• 2018

In this paper the water sensor using a coaxial cavity resonator is designed and manufactured. The water sensor which can sense water drop linearly has been constructed with voltage controlled oscillator(VCO), coaxial cavity resonator, RF switch, RF detector, A/D converter, DAC and micro controller. The operating frequency range of the designed water sensor is from 2.5GHz to 3.2GHz and the input voltage and current source are 24[V/DC] and 1[A]. The designed sensor circuit includes VCO, RF switch, RF detector which varies the frequency characteristics of the devices in the high frequency of 3GHz. And so we should correct the error of the frequency characteristics of those devices in the sensor circuit. To do this, we make the reference path which switches the signals to the RF detector directly without sending it to the resonator. According to the result of simulation and measurement, we can see that there is 0-50MHz difference between simulated resonator frequency and manufactured resonator frequency.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.2
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• pp.1-9
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• 2012

Reinforced concrete buildings will be deteriorated as passed time or effect of an earthquake, etc in main elements. In order to manage such cracks, time and efforts, expense, etc, are required. So micro lead switch sensors are embedding or bonding in flexible specimens, and these are smart elements for diagnostic crack damages by external force such as physical load, dynamic load, etc in this study. The monitoring to crack damages are studied using radio frequency system. If load is received on the center of flexible specimens, embedded and bonded lead switch sensors will be destroyed, and these become to send signals of damages at radio frequency system connected with lead switch sensors. This study is fundamental research of the diagnostic system for architectural elements using radio frequency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.423-424
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• 2011

This paper has proposed a 920 MHz RF front-end for IEEE 802.15.4g SUN (Smart Utility Network) systems. The proposed 920 MHz RF front-end consists of a driver amplifier, a low noise amplifier, and a RF switch. In the TX mode, the driver amplifier has been designed as a single-ended topology to remove a transformer which causes a loss of the output power from the driver amplifier. In addition, a RF switch is located in the RX path not the TX path. In the RX mode, the proposed low noise amplifier can provide a differential output signal when a single-ended input signal has been applied to. A LC resonant circuit is used as both a load of the drive amplifier and a input matching circuit of the low noise amplifier, reducing the chip area. The proposed 920 MHz RF Front-end has been implemented in a 0.18-um CMOS technology. It consumes 3.6 mA in driver amplifier and 3.1 mA in low noise amplifier from a 1.8 V supply voltage.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1511_1512
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• 2009

This paper presents a polarization switching antenna integrated with silicon RF MEMS SPDT switches in the form of a package. A low-loss quartz substrate made of SoQ (silicon-on-quartz) bonding is used as a dielectric material of the patch antenna, as well as a packaging lid substrate of RF MEMS switches. The packaging/antenna substrate is bonded with the bottom substrate including feeding lines and RF MEMS switches by BCB adhesive bonding, and RF energy is transmitted from signal lines to antenna by slot coupling. Through this approach, fabrication complexity and degradation of RF performances of the antenna due to the parasitic effects, which are all caused from the packaging methods, can be reduced. This structure is expected to be used as a platform for reconfigurable antennas with RF MEMS tunable components. A linear polarization switching antenna operating at 19 GHz is manufactured based on the proposed method, and the fabrication process is carefully described. The s-parameters of the fabricated antenna at each state are measured to evaluate the antenna performance.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.8
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• pp.610-618
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• 2017

This paper presents a 868/915 MHz CMOS RF transceiver for the ZigBee application. Using a switchless matching network, the off chip switch is removed to achieve the low cost RF transceiver, and by the elimination of the switch's insertion loss we can achieve the benefits for the RF receiver's noise figure and transmitter's power efficiency at the given output power. The receiver is composed of low-noise amplifier, mixer, and baseband analog(BBA) circuit. The transmitter is composed of BBA, mixer, and driver amplifier. And, the integer N type frequency synthesizer is designed. The proposed ZigBee RF full transceiver is implemented on the $0.18{\mu}m$ CMOS technology. Measurement results show that the maximum gain and the noise figure of the receiver are 97.6 dB and 6.8 dB, respectively. The receiver consumes 32 mA in the receiver mode and the transmitter 33 mA in the transmission mode.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.333-333
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• 2004